The present invention relates to an image recording apparatus provided with a mirror unit disposed between a light condensing lens unit and an exposure table for altering a light path, and more particularly, the invention relates to such image recording apparatus capable of controlling an image magnification by displacing the lens unit and the mirror unit.
An image recording apparatus such as a copying machine generally includes a lens unit for condensing lights which contain imaging information from an original and a mirror unit for reflecting lights passed through the lens unit and focussing an image corresponding to the imaging information on an image recording medium. The employment of the mirror unit is advantageous in that light path can be reversely changed by the light reflection at a mirror, to thereby minimize a distance between the original and the image recording medium, yet obtaining a necessary focal length therebetween, to thus render an overall size of the apparatus compact.
In such the image recording apparatus, the lens unit and the mirror unit are disposed movable relative to a frame in order to change imaging magnification. These units are moved to their positions capable of obtaining a desirable output image having a desirable imaging magnification. To attain this, Japanese Utility Model Publication No. 60-39859 corresponding to U.S. Pat. No. 4,421,405 discloses a copying machine in which a lens unit and a mirror unit are provided movable by a single moving means.
More specifically, a lens bracket which mounts lenses thereon is provided movable by the moving means including a motor, a feed screw, and a nut. Further, a mirror bracket which mounts thereon mirrors is also provided movable. The lens bracket and the mirror bracket are provided with cam followers, respectively, and these cam followers are in abutments with a first cam surface and a second cam surface of a cam plate rotatably supported to a frame of the copying machine. Upon movement of the lens bracket, the cam plate is rotated, so that the mirror bracket is moved. The first and the second cam surfaces are arranged in such a manner that the mirror can be subjected to positioning where an image having a desirable magnification is formed on the image recording medium, when the lens is moved to a desirable position for obtaining the magnification. With the conventional structure, the mirror unit is moved in response to the movement of the lens unit. Therefore, it is not necessary to provide two moving means for moving the respective units, but only the single moving means is required for moving both the lens unit and the mirror unit. Accordingly, simple construction results in the conventional copying machine.
However, in order to move the lens unit and the mirror unit by the single moving means, large driving power must be required in the motor. Further, the feed screw and the nut must have high mechanical strength. Consequently, resultant arrangement may have large weight and becomes costly.